Thomas SIlverstein is considered one of the prison system's most dangerous inmates. He was convicted of killing two fellow inmates and a prison guard. He's suing the Federal Bureau of Prisons for the decades he's spent in isolation.
10 Worst Prisons in the World—5 Are American: San Quentin State Prison, Marin, CA. San Quentin State Prison in Marin County, California, is a hotbed of prison gang activity and California's only death row for men. The Black Guerrilla Family was founded there in 1966 and the Aryan Brotherhood in 1967. Gangs are subdivided by race and region. Not being affiliated with a gang is dangerous, according to an MSNBC look inside the prison.